Breaker strip construction for insulated container



F. KASADY Jan. 12, 1965 BREAKER STRIP CONSTRUCTION FOR INSULATED CONTAINER Filed Jan. 24, 1963 INVENTOR.

FRED KASADY fl$n W, Z

ATTORNEYS United States Patent BREAKER STRIP CONSTRUCTEGN FUR INSULATED CONTATNER Fred Kasady, Huntsville, Ala., assignor to Avco (Jorpora tion, Nashville, Tenn, a corporation of Delaware Filed Jan. 24, 1963, Ser. No. 253,634 4 Claims. (Cl. Mil-9) This invention relates generally to insulated container constructions and, more particularly, to the construction and assembly for'bridging the space between the outer shell and the inner liner of an insulated refrigerator-type cabinet.

Some modifications of foamed polyurethanes have in sulation characteristics sufiicient to make possible low cost, thin-walled, refrigerated cabinets or insulated containers having heat leaks lower than the present thickwalled cabinets insulated with glass or mineral wool. These polyurethanes have excellent adhesive properties, are low in weight, high in structural strength, and have high insulating properties. In accordance with this invention, I use the properties of the polyurethane foam for insulation, and as the means for securing a breaker strip to a cabinet to bridge the space between the outer shell and the inner liner without introducing a heat leak.

It is an object of this invention to provide an improved breaker strip construction wherein the use of fastening devices is entirely eliminated.

Another object of this invention is to provide a con- 7 tainer or cabinet construction in which the insulating material is formed and cast within the double walls of the cabinet not only to provide superior insulating properties, but also to provide the means for bonding a breaker strip to the double walls.

It is another object of this invention to provide a breaker strip assembly which effectively prevents the entrance of moisture and air into the heat insulation of a double walled insulated container or cabinet using foamed-inplace insulating material having bonding and structural properties.

It is still another object of this invention to provide an improved breaker strip construction from the standpoint of appearance and to insure that the breaker strip will be rigidly retained in. position in the normal use of an insulated container or cabinet.

Another object of this invention is to provide a breaker strip for a double-walled container insulated with foamedin-place polyurethane, the breaker strip being fastened to the container by the bonding action of the insulation.

For further objects and advantages of this invention,

reference should now be made to the following specification and to the accompanying drawing in which;

FIGURE 1 is a front elevation of an insulated cabinet constructed in accordance with this invention; and

FIGURE 2 is an enlarged sectional view'taken through the line 22 in FIGURE 1. i

The invention, as illustrated in FIGURES 1 and 2, comprises a cabinet generally indicated at 1% and having a top wall 12, side walls 14 and 16, rear wall 18, bottom wall 20, and a front opening closed by appropriately hinged doors 22 and 24. The entire cabinet is supported on a pair of legs-21 and a pair of wheels 23. The doors of the cabinet are provided with an inner liner 25 and an outer shell 27, while-the walls of the cabinet are provided with an inner liner 26 and an outer shell 28. 1 While liners of sheet aluminum for light weight and Shells of sheet steel for strength were used in cabinets actually reduced to practice, it will be understood that any sheet material having the necessary structural characteristics may be used. A conventional latch 29 is also used. The

space between the inner liners and outer shells is filled with insulation, hereinafter more fully described.

ice

It will be noted that the inner liners and outers shells of the cabinet and the doors are not connected at the edges adjacent the periphery of the front of the cabinet. This space has been provided for the customary purpose of breaking the heat conductivity path from between the inner shells and the outer shells.

For the purpose of bridging the space between the shells and liners around the entire periphery of the cabinet without introducing a thermal connectionbetween the inner and outer shells 26 and 28, a breaker strip 32 is secured, in a manner hereinafter to be explained, to the front edge of the cabinet in the plane of the cabinet opening. For the same purpose, a breaker strip 34 is secured to the doors 22 and 24 at positions opposite the breaker strips 32. A resilient seal 36 is secured around the entire periphery of the breaker strip 32 by any convenient means, such as screws 38. Preferablythe breaker strips 32 and 3d are made of a rigid polymerized resin reinforced with fiber-glass mats to provide high strength and durability.

For the purpose of fastening the breaker strip 32 to the inner liner 26 and outer shell 28 of the cabinet, the front peripheral edge of each is provided with inwardly directed, double reverse bends to form U-shaped channels 4t? and 42 around the periphery of the cabinet, the channels facing outwardly from the cabinet. For purposes not relevant to this invention, the channel 40 at the bottom of the cabinet is formed by an appropriately shaped reinforcing channel iron 43 welded to the outer shell 28 at 45. The breaker strip 32 is channel-shaped, having flanges 44 and 46 extending into and frictionally engaged by the walls of channels 40 and 42, respectively.

At a position adjacent the upper periphery of the channel of each door, the inner liner 25 and outer shell 27 are provided with similar inwardly directed, reverse double bends to provide U-shaped flanges 48 and Sil, re spectively. The edges of the breaker strip 34, which is right angular in cross section, extend into and are frictionally engaged by the walls of the U-shaped channels 48 and 50.

The volumes between the inner liners 26 and outer shells 28 of the cabinet, and the inner liner 25' and outer shell 27 of the doors, are filled with polyurethane foam 30 which is foamed in place. The foam 30 provides the necessary insulation, and also serves to secure the breaker strips 32 and 34 in place. In constructing the cabinet, the inner liners and outer shells are assembled and the breaker strips 32 and 34 are inserted into the respective U-shaped channels. Thereafter the polyurethane foam is introduced into the space between the shells and liners, foaming into the entire volume. .Since the polyurethane foam has adhesive qualities, it serves to bond the breaker strips 32 and 34 to the interior of the respective liners and shells. In addition, the foam increases the pressure on the U-shaped channels in which the breaker strips have been inserted, and this serves to increase the friction on the breaker strips, thereby adhering the breaker strips to the shells and liners.

While many foamed materials can be used in the space between the liners and shells, polyurethane foams are the most desirable of materials available at this time because of their high structural strength, high'insulating value, low weight, and excellent adhesive properties.

Although polyurethane foams do have excellent inherent adhesive qualities, the surface should be clean (free of dirt, oils, greases) and in the case of steel and aluminum (and most other metals), the surfaces should be primed. There are hundred of formulations for producing polyurethane foams. While polyesters foams were first available, polyether foams have generally replaced polyester foams in this field. An exarnple of a formulation for the production of a halogenated hydrocarbon blown foam based follows: i a i polyoxypropylene'sorbitol was prepared having ahydroxyl number of approximately 490 and an acid number of 0.3 or less. A portion of this polyether was mately 780% by weight 2,4-toluene diisocyanate and about 20% by weight, 2,6-to1uene diisocyanate to produce a quasi-prepolymer having an'NCO/OH ratioot 4.5/1.

125 grams of this prepolymer was blended with 1.2

grams of an organosilicone fluid (a surfactant), and 36 grams of trichlorofiuoromethane (F-ll blowing agent):

' 30 seconds.

on a polyetheripolyol is epoxidized polyolefins, may be usedin the place of poly ester. resins. Thermoplastic materials may also be used either with or without reinforcement. :Amongthese are reacted with anisocyanate mixture consisting of approxi- The resulting foam was handleable in 10 minutes at room temperature (75 F.) andthe density of the foam was approximately2 lbs./ft. .t

An example of a formulation for the breaker strip 32 is as follows:

A solution of an unsaturated alkyd in a vinyl monomer suchas styrene, alpha methyl styrene, or vinyl toluene.

wherein the alkyd is a polyester of polyhydric alcohol (such as ethylene glycol, diethylene glycol, dipropylene gylcol or triethylene 'glycol) and dicarboxylic acids (such as phthalic, turnaric, maleic, adipic, succinic) or their anhydrides, and wherein at least of the acids (or anhydrides) are alpha unsaturated, alpha, betapolycarboxylic acids (such as fumaric acid or amleic anhydride). This solution also contains a small inhibiting amount (less than 0.050%) of a material such as Dilute with monomeric styrene to the extent that the styrene total content by Weight will not exceed I This resin may be activated by first blending with 0.1% a

Another method of activation would be by the additertiary butyl catechol or 'hydroquinone. Specifically, the following may be used: Maleic anhydride moles; 1.0 Phthalio anhydride do 1.0 Propylene glycol d'o 2.2 Hydroquinone (inhibitor) "percent" 0.013 Acid No. of alkyd -50 tion 0t.0,92% benzoylperoxide by Weight and placing an 7 ambient of approximately 240 to 255 F, Gel time is approximately one minute.

The glass fibers used may be what "is recognized in the industry as chopped strand mat, unidirectional fibers,

woven roving;or various grades and weaves of glass cloth j and/ or combinations of any of these. i

While examples of particularjbreaker strip and foam formulations havebeen given, it will be recognized that any cellular plastic (e.g., phenolic, epoxy, expanded bead styrene or polyurethane foam) may be used provided it can be placed in the volumes between the inner liners and outer shells and at least partially expanded by either chemical or physical means with resultingadhesivc character. lit-addition, the epoxy resins, which are either V V rnnaon c. jc o DoN, Exa i es;

condensates 0f epichlorohydrinbisphenol)reaction or I acrylic, nylon, etc.

rigid (unplasticized) polyvinyl chloride,.styrene, acrilonitrile-butadiene styrene (ABS It will be seen that'this invention achieves at'least the following advantages: (1) elimination of the-need for blind fastenerssuch as screws, nails, and blind rivets; (2) elimination of any type oilmechanicalfastener'for securing the skins to the edge member; (3) reduction in time and labor for assembling of the panels because. of Sim-- plicity of the fabrication method; (4)- the resultant continuous bond along the joint thatis much more desirable than the intermittent bonds resulting' frorn the use of fasteners. v

Many modifications of this invention will at once'become apparent to persons skilled in the a'rt,iand for that reason it is my intention that the invention not belimited to the structure illustrated 'but only by the scope of the appended claims as interpreted in the light of the prior art; i

What is claimed is: r

1; In a cabinet enclosure, ah insulated wall'c'on prising:

an outer shell; 7 r v an inner liner spaccdfrorn said'outer shelLfsaid outer l shell having an edge adjacent and parallel to an edge of said inner liner, each of said edges h'avinga U: shaped channel formed thereongthe troughof said channel being located in the space between said inner and outer shells, said. trough facin'g'ontwardly therefrom; I a I j rigid low. heat-conducting channel-shaped breaker strip having at least two side walls, said breaker strip 7 V bridging the space between said troughs, the edges'of said side wallsot said breaker strip being frictionally engaged in said tro'ugh's'of said U-shapedchannels;

foamed in place plastic insulating material. in the space defined by "said shelL'. said liner, and said breaker strip, said material adhering to fsaid shell, liner, and brealterstrip, the pressure otlsaid foamed insulating material on said U-shapedchannels increasing'the triction between said breaker strip and resin reinforced with fiberglass.

wherein said breaker strip is made of a rigid polymerized V 1 References Cited by: the Examiner a UNITED STATES PATENTS 2,546,166

GARRETT, Primary Examiner.

plastic), acrilonitrile-styrene, 

1. IN A CABINET ENCLOSURE, AN INSULATED WALL COMPRISING: AN OUTER SHELL; AN INNER LINER SPACED FROM SAID OUTER SHELL, SAID OUTER SHELL HAVING AN EDGE ADJACENT AND PARALLEL TO AN EDGE OF SAID INNER LINER, EACH OF SAID EDGES HAVING A USHAPED CHANNEL FORMED THEREON, THE TROUGH OF SAID CHANNEL BEING LOCATED IN THE SPACE BETWEEN SAID INNER AND OUTER SHELLS, SAID TROUGH FACING OUTWARDLY THEREFROM; A RIGID LOW HEAT-CONDUCTING CHANNEL-SHAPED BREAKER STRIP HAVING AT LEAST TWO SIDE WALLS, SAID BREAKER STRIP BRIDGING THE SPACE BETWEEN SAID TROUGHS, THE EDGES OF SAID SIDE WALLS OF SAID BREAKER STRIP BEING FRICTIONALLY ENGAGED IN SAID TROUGHS OF SAID U-SHAPED CHANNELS; AND A FOAMED IN PLACE PLASTIC INSULATING MATERIAL IN THE SPACE DEFINED BY SAID SHELL, SAID LINER, AND SAID BREAKER STRIP, SAID MATERIAL ADHERING TO SAID SHELL, LINER, AND BREAKER STRIP, THE PRESSURE OF SAID FOAMED INSULATING MATERIAL ON SAID U-SHAPED CHANNELS INCREASING THE FRICTION BETWEEN SAID BREAKER STRIP AND SAID CHANNELS, WHEREBY SAID BREAKER STRIP IS SECURED TO SAID OUTER SHELL AND SAID INNER LINER SOLELY BY THE INCREASED FRICTION AND BY THE ADHERENCE OF SAID MATERIAL TO SAID SHELL, LINER, AND BREAKER STRIP. 